New Raspberry Pi to 1MHz bus interface

[KenLowe]

Ah, I think this was the hazard: trying to approximate a male-to-female extension by combining a male-to-male with a female-to-female will end in disaster.

The small boards I was thinking about building were specifically to address that issue. The boards were going to do the appropriate pin translation. I may still make some, as they shouldn't be very expensive if I combine them with an order for some more Tube level shifters which I'm probably going to have to do shortly.

[Wheel_nut]

I bought some of these to make a 40 Pin Tube extender for my RPi 1B to sit in the Connector well but ended up using Ken's two Header extension instead. They are similar to Hoglets RS ones but have the Retainer/ Ejector Clips.

[KenLowe]

Please be aware that I am now out of stock on the Tube level shifters. I have sufficient stock to cover all current notes of interest, but will need to order up another batch of boards for anyone else who notes interest. I'll advise when these get delivered to me. I still have plenty of 1MHz level shifters if anyone else is interested.

[mph1708]

dp11 wrote
As you can preload the RAM from a file I was wondering if something like bad apple can be ported as you have 480Mbytes of ram to play with.

Bad Apple can be run from Ramdisc (Retroclinic RAMFS) if you use the built in *DTRAP function.
Load to Ramdisc 0 & Ramdisc 2 from DFS Drive 0 & Drive 2 using RCOPY utility. (*RCOPY D0R0 & *RCOPY D2R2)

[cr12925]

I still have plenty of 1MHz level shifters if anyone else is interested.

Please can I buy one of these from you? (How much are they - sorry - I've probably missed an earlier post!)

if you can PM me we can sort it all out no doubt.

Thanks.

C.

[KenLowe]

I still have plenty of 1MHz level shifters if anyone else is interested.

Please can I buy one of these from you? (How much are they - sorry - I've probably missed an earlier post!)

if you can PM me we can sort it all out no doubt.

Thanks.

C.

PM sent.

[tricky]

Has anyone tried to run DOOM on this combo yet?

Does anyone think that using a PI-zero-W to wirelessly update an ADF SCSI image on the 1MHz PI would be feasible - bare metal 'n all.

[dp11]

In theory Wifi might be possible. The problem is finding a clean bare metal Wifi stack .

[KenLowe]

The For Sale forum is open for posting again, so if interested in purchasing a board, please make a post in my For Sale thread.

[aotta]

i'm playing a bit with the 1Mhz interface and it's software, for testing its RAM support, but i can't find the (newbye) info i'm looking for..
i can use the RAM: disc with ramfs120 ROM, and i'd like to use a tool like the MMFS's IMTOD to copy SSD into RAM (or, better, like the *import command available with datacentre), but it seems OSCALL &7F doesn't work for RAM drive 0, and i got a write error with the IMTOD version i modded ..
And, for using the Page mode instead of the byte mode, is needed a specific RAMFS ROM?
Thanks in advance for any info!

[KenLowe]

Sorry, but I'm not going to be able to offer any help with that query as I've not had much experience with using the RAM disk functionality either. Hopefully there are others that can chime in here.

[TheCorfiot]

Hi all, I'm having a difficult time trying to build the firmware release for this using Linux under Windows.

Can anyone please help or can upload a release file for the Pi ZeroW

Many thanks

[KenLowe]

Hi all, I'm having a difficult time trying to build the firmware release for this using Linux under Windows.

Can anyone please help or can upload a release file for the Pi ZeroW

Many thanks

Here's a link to the release file:

https://github.com/dp111/Pi1MHz/archive ... master.zip

Copy the contents of the firmware directory over to your SD card.

[dp11]

Or try the latest version

viewtopic.php?t=19513&start=60

[TheCorfiot]

Thanks for the reply

It looks like my interface board has a fault as even with just the board connected to the 1MHz Bus and no power applied my Model B will not Boot, just get a continuous tone.

the Model B works fine with a real BeebSCSI

[KenLowe]

Thanks for the reply

It looks like my interface board has a fault as even with just the board connected to the 1MHz Bus and no power applied my Model B will not Boot, just get a continuous tone.

the Model B works fine with a real BeebSCSI

I don't think I've ever seen a board fail in that way before (in fact, I've never actually seen a board fail!). Make sure you've got both rows of pins plugged into the 1MHz connector on the beeb. It's easy to get these misaligned.

Edit: Actually, are you using one of my level shifter boards, or are you using a different board?

[TheCorfiot]

I am indeed

I have everything working fine now. schoolboy error.. whoops

[TheCorfiot]

So Time to connect the M5000 Audio to a Stereo Amplifier using a Pi3B and break out cable for Left and Right Audio

it seems the cmdline options are currently ignored as i cant disable the Beebs internal speaker neither adjust the output gain of the Audio which sounds distorted but very quiet and seems to be some kind of processing noise breakthrough

option i'm using in cmdline.txt are

M5000_BeebAudio_Off=x
M5000_Gain=xxxx

this is a fantastic project and hats off to all involved but i'm hoping the Audio quality gets better than i'm currently hearing

Thx

[dp11]

just for clarity the cmdline.txt file should be

Code: Select all

M5000_BeebAudio_Off=1 M5000_Gain=16

If that doesn't work I'll look into it

[TheCorfiot]

just for clarity the cmdline.txt file should be

Code: Select all

M5000_BeebAudio_Off=1 M5000_Gain=16

If that doesn't work I'll look into it

Many thanks, will try it now

[TheCorfiot]

i removed my comments from the cmdline.txt and it works.

Thank you again for shining the way forward.
it sounds very good indeed

[KenLowe]

I don't think I've ever posted a copy of the schematic for this board. That wasn't deliberate. Here's a copy:

Schematic

PCB Layout

3D Render

1MHzAdaptorSchematic.pdf

Schematic PDF

(400.74 KiB) Downloaded 33 times

[aotta]

Thank you for sharing!

[bailey]

I still have plenty of 1MHz level shifters if anyone else is interested.

Please can I buy one of these from you? (How much are they - sorry - I've probably missed an earlier post!)

if you can PM me we can sort it all out no doubt.

Thanks.

C.

PM sent.

Hello Ken, I'm too new to PM at present but would be really keen on a level shifter if you still have any left? Perhaps you can PM me? Thanks

[KenLowe]

Hello Ken, I'm too new to PM at present but would be really keen on a level shifter if you still have any left? Perhaps you can PM me? Thanks

I'll reply to your other post in the For Sale thread...

[KenLowe]

BeebMaster want's to talk to BeebSCSI on Pi1MHz at &FC44..&FC47 (he's created a special build at this address) and a different SCSI host adaptor at &FC40..&FC43. But this doesn't work because the Pi1MHz data level shifter is enabled when either page FC or FD is active, so doesn't allow the other host adaptor exclusive access to the data bus and thereby causes bus conflicts.

See schematic, posted further upthread, that shows how nPGFC and nPGFD are wired through an AND gate (IC4) before routing to the nOE of the level shifter. This is actually a copy of the logic used within the beeb, and was discussed in the early phases of development:

One other point I should have queried earlier relates to the nOE pin on my data bus level shifter. I'm planning to tie this to Gnd and keep the level shifter active at all times on the basis that IC72 on the beeb motherboard will block the 1MHz data bus from the beeb databus when not in use. Does that sound like a reasonable plan? Alternatively, I could just repeat the CE switching logic of IC72 (using two diodes and a resistor).

To get this working I need to prevent Pi1MHz from keeping the data level shifter active when it's not actively writing to the data bus. But this would require another output from the Pi, and there doesn't appear to be any spare I/O.

I was wondering if any of the I/O could be repurposed? Having a look through the I/O, the one signal that jumped out at me was the NMI signal. Does Pi1MHz drive the NMI signal at all? If that's not available, what other options are open to us, with the limited space on the PCB.

[BeebMaster]

Thanks Ken, look forward to seeing how it progresses.

I'm not sure if it's too elementary to be even be worth saying, but dp11's original design using only resistors and diodes does work in allowing other devices at different addresses to exist on the 1MHz bus. Not that I am claiming a triumph of the old faithful through hole over modern new-fangled surface mount or anything...

[KenLowe]

I'm not sure if it's too elementary to be even be worth saying, but dp11's original design using only resistors and diodes does work in allowing other devices at different addresses to exist on the 1MHz bus.

I think that will be because the Pi data lines are going tri state when the Pi is not reading or writing. This is what I need the Pi1MHz data level shifter to do as well.

[Alow2004]

Hello,
Is it possible to buy one of those interface.
The goal is to interface it with an archimedes 1Mhz I/O module interface, so a little bit different of standard usage
With a RPI 4B
Thanks for your response.
PS: I live in luxembourg, my address is :
(address removed by a forum moderator)
Luxembourg.

I would like to would interface to use keyboard, mouse, floppies, and maybe cards from the archimedes to drive the PI.

Best regards.
Congratulation for your wonderful job!

Edited by 1024MAK to remove the address. Mark

[KenLowe]

Hi Alain,

I've taken a note of your address. Can I suggest that you edit your post and remove your address for security reasons. I'll drop you a PM later with my email address so you can contact me directly.